[PATCH 3/3] tcm/iblock,fileio: Fill in remaining Block Limits VPD from rq->limits

["Nicholas A. Bellinger" <nab@linux-iscsi.org>]

From: Nicholas Bellinger <nab@linux-iscsi.org>

This patch updates iblock_create_virtdevice() and fd_create_virtdevice()
to set the following device attributes from struct request_queue->limits values
when the generic Linux/Block Discard logic is enabled via blk_queue_discard()==1:

	max_unmap_lba_count = q->limits.max_discard_sectors;
	max_unmap_block_desc_count = 1
	unmap_granularity = q->limits.discard_granularity;
	unmap_granularity_alignment = q->limits.discard_alignment

Here is how it looks in action with sg_vpd with TCM_Loop -> TCM/IBLOCK ->
scsi_debug w/ TPE + TPU enabled:

target# sg_vpd --page=0xb0 /dev/sdh
Block limits VPD page (SBC):
  Maximum compare and write length: 0 blocks
  Optimal transfer length granularity: 1 blocks
  Maximum transfer length: 1024 blocks
  Optimal transfer length: 1024 blocks
  Maximum prefetch, xdread, xdwrite transfer length: 0 blocks
  Maximum unmap LBA count: 1024
  Maximum unmap block descriptor count: 1
  Optimal unmap granularity: 4096
  Unmap granularity alignment valid: 1
  Unmap granularity alignment: 4

Many thanks to Martin Petersen for answering questions here!

Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
---
 drivers/target/target_core_file.c   |   14 ++++++++++++++
 drivers/target/target_core_iblock.c |   15 ++++++++++++++-
 2 files changed, 28 insertions(+), 1 deletions(-)

diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index 8864f8f..d0afb50 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -241,6 +241,20 @@ static struct se_device *fd_create_virtdevice(
 	 */
 	if (S_ISBLK(inode->i_mode)) {
 		if (blk_queue_discard(bdev_get_queue(inode->i_bdev))) {
+			struct block_device *bd = inode->i_bdev;
+			struct request_queue *q = bdev_get_queue(bd);
+			
+			DEV_ATTRIB(dev)->max_unmap_lba_count =
+					q->limits.max_discard_sectors;
+			/*
+			 * Currently hardcoded to 1 in Linux/SCSI code..
+			 */
+			DEV_ATTRIB(dev)->max_unmap_block_desc_count = 1;
+			DEV_ATTRIB(dev)->unmap_granularity =
+					q->limits.discard_granularity;
+			DEV_ATTRIB(dev)->unmap_granularity_alignment =
+					q->limits.discard_alignment;
+
 			DEV_ATTRIB(dev)->emulate_tpu = 1;
 			printk(KERN_INFO "FILEIO: Enabling BLOCK Discard"
 				" and TPU=1 emulation\n");
diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index 80b9880..2dae7fd 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -227,8 +227,21 @@ static struct se_device *iblock_create_virtdevice(
 	 * in ATA and we need to set TPE=1
 	 */
 	if (blk_queue_discard(bdev_get_queue(bd))) {
+		struct request_queue *q = bdev_get_queue(bd);
+
+		DEV_ATTRIB(dev)->max_unmap_lba_count =
+				q->limits.max_discard_sectors;
+		/*
+		 * Currently hardcoded to 1 in Linux/SCSI code..
+		 */
+		DEV_ATTRIB(dev)->max_unmap_block_desc_count = 1;
+		DEV_ATTRIB(dev)->unmap_granularity =
+				q->limits.discard_granularity;
+		DEV_ATTRIB(dev)->unmap_granularity_alignment =
+				q->limits.discard_alignment;
+
 		DEV_ATTRIB(dev)->emulate_tpu = 1;
-		printk(KERN_INFO "IBLOCK: Enabling BLOCK Discard"
+		printk(KERN_INFO "IBLOCK: Enabling BLOCK Discard support"
 				" and TPU=1 emulation\n");
 	}
 
-- 
1.5.6.5